A lovable, smoothed-out Michelin Man, Baymax is a robo-nurse with seemingly unlimited power and the sidekick of our hero Hiro.
Photograph: Disney/LFI/Photoshot

They called Buster Keaton the Great Stoneface. I guess Baymax is … the Great Vinylface? The heart and soul of Big Hero 6, Disney and Marvel’s first animated team-up, Baymax (voiced by Scott Adsit) is a kind, pudgy balloon-man programmed to stop at nothing to patch you up, physically or psychologically. His lumbering waddle, Spock-like logic and eternally blank expression (something of a kiddie Kuleshov effect) are a perfect recipe for comedy.

A lovable, smoothed-out Michelin Man, Baymax is a robo-nurse with seemingly unlimited power and the sidekick of our hero Hiro. But Hiro (voiced by Ryan Potter) didn’t create Baymax, his older brother Tadashi did. After Tadashi dies in a suspicious explosion, Hiro, already orphaned, is now double-abandoned, so it’s going to take an adventure of inter-dimensional proportion to get him to heal.

Big Hero 6, very loosely based on a Marvel comic tangential to the core universe of the Hulk and Fantastic Four, is set in San Fransokyo, a pleasant mashup of American and Japanese cultural tropes. Come get a latte at the Lucky Cat Cafe, in the shadow of a bridge that looks an awful lot like the Golden Gate crossed with traditional Shinto torii. Hiro is a kid science whiz, already done with high school by age 14. When we first meet him he’s wasting his gift on underground Real Steel-like robot fights. Tadashi convinces him that the Epcot Centre-like San Fransokyo Institute of Technology isn’t “nerd school,” but, in fact, a haven of cutting-edge fun and excitement. A great deal of Big Hero 6’s first act is devoted to convincing you, the viewer, that “science is rad!”

Any and all eyerolls will be halted by the eventual unboxing of Tadashi’s project, the healthcare robot Baymax. The simplicity of its design and Adsit’s flat line delivery work to great effect. In all my years of moviegoing I don’t know that I’ve seen an audience imprint themselves on a character quite so quickly. It wasn’t 15 seconds until little kids in the crowd were cooing “Baymax!” They’re going to sell a squillion toys.

When Hiro and Baymax decide to go all Scooby Doo and investigate the mystery of the deadly fire, all concerns about the hackneyed, predictable plot are deflated as we watch Baymax deliberately bounce through the mayhem. “I am not fast,” he calmly informs Hiro as a villain gives chase. This curt line, offered with zero emotional spin, is one of the funniest moments I’ve seen in a movie this year. And every single kid in the world will be saying this during gym for months.

The bad guy has access to Hiro’s invention: Microbots, little gizmos that represent one of Big Hero 6’s main problems. The movie pays great lip service to the hard work of innovation, but obnoxiously presents science as facile magic. The Microbots are ESP-powered nanotechnology that can do virtually anything, and were created in a flash by a kid during a musical montage. Later, when Hiro decides to refit his school chums into superheroes (the group of five plus Baymax making a “big hero 6”) he does it through just a few taps on a keyboard. “We’ll have Baymax scan everyone in the city!” is an example of his problem solving, making the already far-fetched tech of Iron Man seem peer-reviewed.

Granted, when the team assume their alter egos, including a stoner dude as a kaiju and a Battle of the Planets-like pixie with a computer purse, it makes for a quite adorable kid version of the Avengers. Alas, that also means an interminable third act featuring a deadly, mayhem-causing portal to another dimension. It’s always portals.

I could have used a lot less of Big Hero 6’s video game-inspired final act, but Disney is looking to establish a franchise here, so a degree of colouring within the lines is expected. The San Fransokyo cityscape and huggable Baymax are more than enough to differentiate this film from usual fare. When Baymax is low on battery power he becomes a silly, Chaplin-esque drunk. Why would anyone program him that way? No logical reason. But his data chip, the one that establishes his personality, emerges from a drive beside his left breast, meaning that in order to change he must literally open his heart. And when he looks at you with those round, empty eyes you’ll do just the same.

• Comments have been reopened to time with this film’s Australian release